Abstract
Introduction: There are various doses, durations, and strains of bacillus Calmette-Guérin (BCG) intravesical instillation therapy, but optimal treatment has not yet been established. We retrospectively investigated the efficacy and safety of low-dose BCG therapy for non-muscle-invasive bladder cancer (NMIBC) and carcinoma in situ (CIS) in a multicenter study. Methods: From 1991 to 2019, 323 patients who received BCG therapy to prevent recurrence of NMIBC were analyzed as group A. Similarly, 147 patients who received BCG therapy for the treatment of CIS were analyzed as group B. Patients received low- or full-dose Tokyo-172 strain or full-dose Connaught strain, and the three strains were compared. Survival curves were estimated by the Kaplan-Meier method, and independent risk factors for intravesical recurrence were examined by multivariate logistic regression. Results: Recurrence-free survival (RFS) in group A was significantly better for the Connaught strain than the low-dose Tokyo-172 strain (p = 0.026), but not between the low- and full-dose Tokyo-172 strains (p = 0.443). RFS of group B, cancer-specific survival, and progression-free survival in both groups did not show statistically significant differences. Logistic analysis of group A showed that for intravesical recurrence, only pT1 was a significant risk factor, and there were no differences between the BCG strain and dose and no significant factors in group B. There were also no differences in the completion rate in both groups, but adverse events such as urinary frequency and feeling of residual urine were significantly lower with the low-dose Tokyo-172 strain. Conclusion: There was no difference in efficacy between the low- and full-dose Tokyo-172 strains, but to minimize adverse events, the low-dose Tokyo-172 strain may be worth considering.